Fastener driving tool

ABSTRACT

There is provided a fastener driving tool having a control valve arrangement including a trigger valve, a cycling valve and a safety valve. The cycling valve is adapted to repetitively cycle the driving piston of the fastener driving tool through power and return strokes or to provide for single-cycling of the piston through a drive and return stroke in response to the position of the trigger. In addition there is provided an arrangement wherein the operation of the piston is arrested when the bumper cushioning the power stroke of the piston is excessively worn.

United States Patent Novak Feb. 1,1972

[54] FASTENER DRIVING TOOL [72] inventor: Raymond F. Novak, SchillerPark, 111.

[73] Assignee: Fastener Corporation, Franklin Park, 111.

[22] Filed: June 30,1969

[21] Appl.No.: 837,696

[52] U.S.Cl ..91/220,91/226,91/298, 91/300,9l/308,91/356 [S1] 1nt.Cl..F01b 25/04, F01l2l/04, F01l25/06 [58] FieldoiSearch ..9l/220, 300,399, 226, 298, 91/308, 356

[56] References Cited UNITED STATES PATENTS 3,278,103 10/1966 Juilfsetal ..91/220 3,278,104 10/1966 Bechtet al.. ....91/220 3,313,213 4/1967Wandel ..9l/399 3,329,068 7/1967 Klaus ..91/399 3,396,636 8/1968 Bade3,496,835 2/1970 Siegmann ..9l/300 Primary Examiner-Paul E. MaslouskyAttorneyMason, Kolehmainen, Rathbum & Wyss [5 7] ABSTRACT 19 Claims, 12Drawing Figures /05 I l l i 1 l8? a l {I #6 W /75 7% I l I194 M8 mag: It w //e 454 t a l l PATENIEU FEB 1872 sum 1 or 3 FIG. I

ATTORA/EYS- FASTENER DRIVING TOOL This invention relates to a fastenerdriving tool, and more particularly to a fastener driving tool includingnew and improved control and cycling means therefor.

Pneumatic fastener driving tools on the market today may be of the typethat, when the trigger is depressed, the drive piston and connectedfastener driving blade move through a power or drive stroke of afastener driving operation and are returned upon completion thereof by asuitable piston return means. Such piston and driving blade are cycledthrough a single cycle of power and return strokes upon depression ofthe trigger, whether or not the trigger has been released to provide forsingle-cycle operation of the tool.

Fastener driving tools also are known which are provided with means forrepetitively cycling the driving piston and driving blade through itscycle of power and return strokes so long as a trigger valve ismaintained depressed, to provide for autofiring or multiple-firing ofthe tool. Means may be provided in such a multiple-fire tool to providefor single-firing thereof if desired.

Heretofore it has been known to provide means for adjusting theautofiring rate of the too]. However such autofiring adjusting means incommercially known tools has adjusted or restricted the single-firingrate of the tool. Such tools are restricted to the autofire repetitiverate which may be a handicap when a few fasteners are required to befired at a higher rate of speed into a particular area of the workpiece.

Moreover it has been customary to provide a bumper or cushion for thedrive piston at the end of its drive stroke. However when the fastenerdriving tool is operated in the autofire position for long periods oftime, the bumper becomes hot and deteriorates rapidly.

Accordingly one object of the present invention is to provide a new andimproved pneumatically actuated fastener driving tool wherein theautofire rate thereof may be adjusted without affecting the single-firerate of the tool.

Another object of the present invention is to provide a new and improvedfastener driving tool wherein the tool is rendered inoperative if thepiston bumper has deteriorated beyond useful limits.

Another object of the present invention is to provide a new and improvedpneumatically actuated fastener driving tool.

Yet a further object of the present invention is the provision of afastener driving tool having a new and improved control valve permittingease of autofire selection or single-fire selection by the operator.

In accordance with the present invention there is provided a new andimproved fastener driving tool of the general type including a housinghaving a cavity defining a fluid reservoir and a cylinder in thehousing. A driving piston having a driving blade is slidably mounted inthe cylinder. A main valve of known type is provided for controlling theadmission of fluid to and the exhaust of fluid from one end of thecylinder so as to drive the piston through a power or drive stroke andto permit the return of the piston through a return stroke.

In accordance with the present invention there is provided an improvedcontrol valve including a safety valve, a trigger valve, and a cyclingvalve. The cycling valve is movable between a first position permittingcontrol of the driving piston through a driving stroke by the triggervalve and safety valve, to a second position providing for the return ofthe piston upon completion of a driving stroke. To this end a signal isreceived by the cycling valve representative of the completion of adriving stroke. When the tool is operatively selected for autofire, aback pressure on the cycling valve prevents shifting of the cyclingvalve until the signal fluid builds up to an amount sufficient toovercome the back pressure. Thus throttling of the signal fluidpassageway will vary the repetitive firing rate of the tool. When it isdesired to fire the tool as a single-fire tool, the back pressure on thecycling valve is removed and the cycling valve will shift upon the firstpressure buildup to the valve. Thus throttling or restriction of thesignal fluid passageway is ineffective to alter the cycling of the toolthrough the single-fire cycle.

In accordance with another feature of the present invention, the drivingpiston is returned through its return stroke by a pressure buildup offluid within a return air chamber. The pressure buildup in the chamberresults when passages in the piston line up with passages through thecylinder wall leading into the return air chamber. However, in the eventthat the bumper at the end of the power stroke has deteriorated. airfrom the return air chamber will discharge through the same passagewayinto the cylinder above the piston and exhaust to the atmosphere throughan exhaust valve in the cylinderpreventing return cycle of piston totake place. Thus the operator will be apprised of thefact that the toolrequires servicing or maintenance before itcan be further operated.

For a better understanding of the present invention, reference may behad to the accompanying drawings wherein:

FIG. 1 is a fragmentary elevational view of a fastener driving toolaccording to the present invention illustrated in its normal or at restposition;

FIG. 2 is a fragmentary view of the improved fastener driving tool shownwith the driving piston at the end of a driving stroke; I

FIG. 3 is a fragmentary view of the improved fastener driving toolsimilar to that shown in FIG. 2 but illustrating a deterioratedcushioning bumper;

FIG. 4 is a fragmentary view of the valve arrangement taken along line4-4 of FIG. 1;

FIG. 5 is a cross-sectional view of the valve arrangement according tothe present invention, taken along lines 55 of FIG. I;

FIG. 6 is a cross-sectional view of the trigger valve of the improvedfastener driving too] taken along line 66 of FIG. 5;

FIG. 7 is a cross-sectional view of the cycling valve of the improvedfastener driving tool taken along line 7-7 of FIG. 5;

FIG. 8 is a cross-sectional view of the control valve housing of FIG. 1,illustrating the throttling mechanism, taken along line 808 of FIG. 5;

FIG. 9 is a cross-sectional view of the control valve mechanism of thefastener driving tool of FIG. 1, illustrated in the single-firearrangement;

FIG. 10 is a fragmentary cross-sectional view of the control valvearrangement of FIG. 9, illustrating the cycling valve in its positionfor the return of the piston through a return stroke;

FIG. 11 is a cross-sectional view of the control valve of the improvedfastener driving tool illustrated in the autofire position; and

FIG. 12 is a perspective view of the control valve housing of theimproved fastener driving tool.

Referring now to the drawings, particularly to FIG. I, there isfragmentarily illustrated a fastener driving tool, generally illustratedas I0, which embodies the control valve assembly and bumper arrangementaccording to the present invention. The tool 10 may be of knownconstruction, and, as illustrated, comprises a housing 12 including agenerally vertically extending head or forward portion and a rearwardlyextending hollow handle portion having a cavity defining a fluidreservoir 16. Pressurized fluid such as compressed air is supplied tothe fluid reservoir 16 of the tool by a suitable flexible line. Thedrive system for the tool 10 includes a main or power cylinder 18mounted within the head portion of the housing I2 and having an openupper end that is adapted to be selectively connected to the reservoirI6. The open upper end of the cylinder 18 is in engagement with a mainor cylinder valve assembly 20 of a known type, under the control of acontrol valve assembly 22 according to the present invention. A fastenerdriving assembly 24 slidably mounted in the cylinder 18 includes a mainor drive piston 26 and has connected thereto a depending drive blademember 28. The fastener driving assembly 24 is normally biased to aposition with the piston 26 adjacent the cylinder valve assembly 20. Anexhaust valve assembly indicated generally as 32 is provided forcontrolling the selective connection of the upper end of the cylinder 18to the atmosphere.

When the tool is to be operated, compressed fluid from the reservoir 16enters the upper open end 18a of the cylinder 18 and drives the fastenerdriving assembly 24 downwardly to engage and set a fastener or nail 34supplied to a drive track 36 in a nosepiece or nosepiece structure 38.The flow of compressed fluid in the upper end of the cylinder 18 iscontrolled by the main valve assembly 20, which includes a verticallymovable ring member 40 defining a valve element, and having a sealingring 42 engageable with the upper open end 18a of the cylinder 18. Thecylinder side of the ring member 40 is continuously in communicationwith the fluid reservoir 16 through a suitable passageway 44 so thatpressurized fluid continuously acts against the cylinder side of thering member 40 tending to displace the ring member 40 from the edge 18aof the cylinder 18.. However pressurized fluid is also introduced to theopposite side of the ring member 40 through a passageway 48 while thefastener driving tool 10 is in a static or at rest position. Thedifferential pressure acting on the ring member 40 is effective tomaintain the ring member 40 down, in a closed position, with the sealingring 42 against the top 18a of the cylinder 18. However if thepressurized fluid above the ring member 40 is discharged, thepressurized fluid acting through the passageway 44 is effective tounseat the ring member 40 from the edge 18a of the cylinder 18 to dumppressurized fluid into the top of the main cylinder 18 and to drive thedrive piston 26 through the drive stroke.

When the fastener driving tool is at rest, or during the return strokeof the drive piston, the upper open end of the cylinder 18 is exhaustedto the atmosphere through the exhaust valve assembly 32. In theillustrated embodiment the exhaust valve assembly includes a disc-shapedvalve member 50 having a resilient valve element 52, one edge 52a ofwhich is engageable with an inwardly projecting lip 40a of the ringmember 40 when the ring member is displaced upwardly to provide a sealtherebetween. The valve element 52 is spaced below the inner surface ofa downwardly projecting boss 54 defined in a cap 56 of the tool 10. Thedownwardly projecting boss has a plurality of exhaust passageways 58providing for the exhaust of the fluid when the ring member 40 is in itsdownward position.

To provide for the return stroke of the fastener driving assembly 24,there is provided a return air chamber 60 communicating with the lowerend of the cylinder 18 through a plurality of fluid inlet ports 62 and aplurality of fluid outlet ports 64. Moreover the drive piston 26 isprovided with a pair of spaced O-rings 66 and 68, and a passageway 70that communicates from the upper surface of the piston 26 openingbetween the O-rings 66 and 68. The smaller passageway 70 defines a valveor passage for the flow of return fluid from above the piston 26 intothe return air chamber 60 whenever the passageway 70 is aligned with thefluid inlet ports 62, as illustrated in FIG. 2. Thus it will beunderstood that in the normal operation of the fastener driving tool 10,the working fluid above the piston 26 will flow through the passageway70 and fluid inlet ports 62 into the return air chamber 60, and willthereafter flow through the fluid outlet ports 64 below the piston 26 todrive the piston 26 back through its return stroke. For efficient pistonreturn, restricting passage 70 should be smaller than passage throughports 64. The fluid pressure drop through port 64 should be appreciablyless than that through port 70, otherwise, fluid will escape from thisport rapidly to atmosphere when the poppet is closed and the exhaustvalve 52 is open. In this event the piston will not shift initiallyblocking passage between ports 62 to 70, thereby allowing escape offluid from the storage chamber 60 until it is depleted. The fluidpressure drop should be less through the port beneath the piston thanabove, otherwise it will not be displaced sufficiently, blocking ports62 and 70 and allowing the full return stroke. A greater volume of fluidwill exit from chamber 60 to the bottom of the driver thus shifting itupwardly and closing off flow from passage 62 to above the driver and toatmosphere. Residual return fluid below the piston 26 will be dissipatedto atmosphere by bleeding through a bleed opening 71 formed between thedrive blade 28 and a washer 72.

In accordance with the customary practice. there is provided a resilientcushioning member or bumper 74 in the lower end of the cylinder 18,defining a stop for the piston 26 when it is at the end of its drivestroke. At this time the passageway 70 will be aligned with the fluidinlet port 62 as indicated in FIG. 2.

In the event that the bumper 74 has deteriorated, so that the piston 26moves down the cylinder 18 further than desired, to the positionillustrated in FIG. 3, the passageway 70 will no longer align with thefluid ports 62; the O-ring 66 of piston 26 will have cleared past thefluid ports 62. Thus any pressurized fluid entering the return airchamber 60 as the piston 26 travels past the ports 62 will be dischargedinto the cylinder 18 above the piston 26 and exhausted to atmospherethrough the exhaust valve assembly 32, and the piston 26 will not returnupon completion of a drive stroke. Under normal conditions, fluid willleak only momentarily through the small port 70, until the fluidpressure beneath the piston discharging through the least resistant port64, raises the piston to its fully retracted position. When the pistonis displaced below the larger port 64, as caused by deterioration of thebumper, a much higher proportion of the stored fluid will escape abovethe piston as this flow is no longer restricted through the smallpassage 70. A substantial decrease in chamber 60 fluid pressure willresult, preventing the full return of the piston. The tradesmen will berequired to replace the fastener driving tool and to have the toolserviced so that the bumper 74 may be replaced.

The control valve assembly 22 includes a trigger valve 78, a safetyvalve 80. and a cycling valve 82. As is known in the art, the safetyvalve includes an actuator rod 84 connected by linkage to move down whenthe nosepiece 38 of the fastener driving tool is in engagement with theworkpiece, and is programmed to prevent firing or cycling of the toolwhen the nosepiece 38 is not in engagement with the workpiece. Thetrigger valve 78 includes a trigger 86 which may be depressed to a firstposition, illustrated in phantom as 86 in FIG. 6. and represented inFIGS. 9 and 10 to provide for single-fire operation of the tool 10, andfurther depressible to a second position illustrated in phantom in FIG.6 as 86", represented in FIG. 11 wherein there is provided autofireoperation of the tool 10 so long as the trigger is held in the depressedposition. Any suitable means may be provided for positioning the triggerdepression into its intermediate position; however in the illustratedembodiment there is provided a pneumatic bias to the trigger 86 suchthat for depression of the trigger 86 to its intermediate position 86the trigger 86 is brought to bear against an outwardly biased piston 90riding within a cylinder 92 communicating with the fluid reservoir 16through a passageway 94. In order to further depress the trigger 68 intoits position 86", the trigger 86 must overcome the resisting bias of thepiston 90, depressing the piston 90 to the position illustrated inphantom in FIG. 6. The cycling valve 82 is effective to control thereturn movement of the fastener driving assembly 24 through its returnstroke and will control the return thereof through a single cycle orthrough multiple repetitive cycles as called for by the function of thetrigger 86.

Advantageously the control valve assembly 22 including the trigger valve78, safety valve 80 and cycling valve 82 is housed within one compactremovable valve housing 98, best illustrated in FIG. 12. Passageways maybe die cast into the housing 98 and the housing 98 is readily secured tothe housing 12 with the upper end thereof retained by a suitable pin 100and the lower end thereof fastened by suitable screws or bolts I02.Advantageously the valve housing 98 may be readily removed for repairand replacement.

Referring now to the valves in the control valve assembly 22, thecycling valve 82 includes a differential cycling valve cylinder 108defined within the valve housing 98, closed at both ends, and slideablyreceiving a cycling valve spool or element 110 of a differentialdiameter type. The cycling valve cylinder 108 has an upper largediameter portion 108a and a lower small diameter portion 108b. Thecycling valve spool 110 has an enlarged upper portion 1100 receivedwithin the large diameter portion 108a, and a lower small diameterportion 11% slideably receivable within the small diameter portion l08b.Additionally the cycling valve spool 1 10 is provided with a largesealing ring 112 defining a valve piston and a pair of spaced smalldiameter O-rings 114 and 116 spaced apart from the O-ring 112 andcarried on the small diameter portion 11%. A first cycling port 118opens into the end of the small diameter portion 108!) of the valvecylinder 108. A second cycling port 48a opens into the lower end of thesmall diameter portion 108!) of the valve cylinder 108 intermediate thestroke of the O-ring 116, and connects through passageway 48 to theupper surface of the ring member 40 of the cylinder valve assembly 20. Athird cycling port 122 opens into the small diameter portion 108b of thevalve cylinder 108 intermediate the stroke of the small diameter O-rings114 and 116. A fourth cycling port 124 opens into the valve cylinder 108intermediate the large O-ring 112 and the spaced small O-ring 114throughout their travel. A fifth cycling port 126 opens into the end ofthe large diameter portion 108a of the valve cylinder 108 and isconnected by a signal passageway 128 (FIG. 8) to a source of signalfluid, here shown as connected to the return air chamber 60.

The trigger valve 78 includes a valve cylinder 140, open to theatmosphere at its upper end, and slideably receiving a trigger spoolvalve 142, the upper end of which is engaged by a projecting finger 86aof the trigger 86 to be actuated thereby. The trigger spool valve 142contains three spaced O-rings 144, 146 and 148. The trigger spool valve142 is movable from a normal position, with the tool at rest, asillustrated in FIGS. 5 and 6, to an intermediate or single-fire positionas illustrated in FIGS. 9 and 10, to a fully depressed or autofireposition as illustrated in FIG. 11. The valve cylinder 140 is providedwith an annular exhaust passageway 150 formed around the upperprotruding end of the valve spool 142. A first trigger port 152 opensinto the valve cylinder 140 intermediate the normal and displacedpositions of the valve O-ring 144. A second trigger port 154 opens intothe valve cylinder 140 intermediate the stroke of the trigger spoolvalve 142 between the valve O-rings 144 and 146. A third trigger port156 opens into the valve cylinder 140 intermediate the travel of thevalve O-ring 146 from the single-fire position to the autofire positionand is connected to the fourth port 124 of the cycling valve 82 by apassageway 158. A fourth trigger or exhaust port 160 opens into thevalve cylinder 140 intermediate the travel of the valve O-rings 146 and148, and exhausts to the atmosphere. A fifth trigger port 162 opens intothe closed lower end of the valve cylinder 140, and is connected to thesecond trigger port 154 by a passageway 164, and to the reservoir by apassageway 165.

Referring now to the safety valve 80, the safety valve 80 is defined bya safety valve cylinder 172 containing a safety spool valve 174 joinedto the actuating rod 84 for movement therewith. The safety spool valve174 carries three spaced 0- rings 176, 178 and 180 defining or forming apair of annular passageways 182 and 184 therebetween. A first safetyport 186 opens into the annular passageway 182 formed by the 0- rings176 and 178, and is connected to the first trigger port 152 by apassageway 188. A second safety port 190 opens into the valve cylinder172 intermediate the travel of the O-ring 178, and is connected to thefirst port 118 of the cycling valve 82 by a passageway 192, A thirdsafety port 194 opens into the valve cylinder 172 into the annularpassageway 184, and is connected to the trigger ports 154 and 162 by apassageway 196, and further interconnects these trigger ports with thethird port of the cycling valve 82 through a passageway 198. Anadjustable needle valve 204, FIG. 8, restricts the fluid flow throughthe signal passageway 128, thereby providing the regulation of therepetitive cycling rate of the tool 10 when in the autofire position.

From the above detailed description, the operation of the control valveassembly 22 is believed clear. However, briefly, it will be understoodthat the control valve assembly has three operable positions; namely anormal position, with the valve elements as illustrated in FIG. 5; asingle-fire position with the trigger and safety valve as shown in FIGS.9 and 10, and the cycling valve cycling between the positions alsotherein indicated; and an autofire position, with the safety and triggervalves in the position illustrated in FIG. 11 and the cycling valvemovable between the position illustrated in FIG. 11 and the positionillustrated in FIG. 10 repetitively so long as the trigger 86 ismaintained in the fully depressed position.

More specifically, and referring to the normal or at rest position ofthe tool, in this position the upper surface of the ring member 40 ismaintained at reservoir pressure through the trigger port 162,passageway 196, safety port 194, annular passageway 184, safety port190, passageway 192, port 118 in the cycling valve, port 48a, andpassageway 48 to maintain the ring member 40 down and closed against thetop 18a of the cylinder 18.

The tool 10 will not operate unless both the trigger valve 78 and safetyvalve are actuated. Thus if the safety valve 80 alone is actuated, thenthe flow of pressurized fluid between the safety ports 190 and 194 willbe blocked by the O-ring 178, but the upper surface of the ring member40 will not be exhausted to atmosphere and thus the tool 10 will notfire. More specifically, the upper surface of the ring member 40 remainspressurized by the fluid supplied to the port 190 over the fluidconveying system including the passages 196, 164, the port 154, theclearance between the O-rings 144 and 146, the port 152, the passage188, the port 186, and the clearance between the O-rings 176 and 178.

When it is desired to operate the tool 10 as a single-fire tool, it isnecessary that the safety valve 80 be actuated to the operativeposition, as illustrated in FIG. 9, and that the trigger valve 78 beactuated to its intermediate position as also therein illustrated. Inthis position the upper surface of the ring valve 40 will be exhaustedto atmosphere through the passageway 48, cycling ports 48a and 118,passageway 192, safety ports 190 and 186, passageway 188, trigger port152, and through the exhaust passageway thus opening the cylinder valveassembly 20 and driving the fastener driving member 24 through afastener driving cycle. At the same time the differential portion of thecycling valve 82, intermediate the large and small O-rings 112 and 114.will be exhausted to atmosphere through the cycling port 124, passageway158, trigger port 156, and trigger port 190. As soon as the drive piston26 reaches the end of its drive stroke, the return air chamber 60 willbe pressurized by the flow of pressurized fluid through the passageway70 and fluid inlet port 62. The pressure will instantly act on the upperlarge diameter portion of the cycling valve 82 through the passageway128 and cycling port 126. Since there is no counter bias to the cyclingvalve 174, the cycling valve 82 will instantly shift from the positionillustrated in FIG. 9 to the position illustrated in FIG. 10. At thistime pressurized fluid will flow from the reservoir by means of thetrigger port 162, passageway 198, and cycling ports 122 and 480 throughpassageway 48 to the upper surface of the ring member 40 to close thering member 40 against the open upper end 18a of the cylinder 18. Thispermits exhaust of the upper end of the cylinder 18 and the pressurizedfluid which has now built up in the return air chamber 60 will beeffective to return the piston 26 to its normal or at rest position.Moreover since there is no force on the cycling valve 82 tending toreturn the cycling valve 82 back to its original position, it willremain in its displaced position so long as the trigger is held in thesingle-fire condition. Upon release of the safety and/or the triggerfrom the single-fire position, pressurized fluid will be admitted to theclosed lower end of the cycling valve to the port 118, in like manner asdescribed in connection with FIG. 5, and the cycling valve 82 will bereturned to its normal position.

When it is desired to operate the tool 10 in the autofire position, itis necessary that the trigger 86 be fully depressed against theresisting bias of the piston 90, depressing the trigger spool valve 142to the position illustrated in FIG. 11. Under these conditions thereis'provided a return bias to the cycling valve 82; specifically thedifferential portion of the cycling valve spool 110 will be connected toreservoir pressure through the port 124, passageway 158, trigger ports156 and 154, passageway 164, and trigger port 162 which is connected tothe reservoir through the passageway 165. As soon as the piston 26reaches the end of its driving stroke, as illustrated in FIG. 2, fluidpressure will build up within the return air chamber 60. This pressurewill be transmitted through the signal passageway 128, past the needlevalve 204, and into the upper closed end of the portion 108a of thecycling valve cylinder 108. As soon as the pressure in this end of thevalve cylinder 108 builds up to a sufficient magnitude to overcome thereturn bias on the differential diameter portion of the valve spool 110,the cycling valve spool [10 will shift to its down position, asillustrated in FIG. 10. Because the rate of pressure buildup in thevalve cylinder 108 from the signal passageway 128 may be regulated byadjusting the needle valve 204, the speed at which the cycling valvespool 110 shifts can be controlled, and thus the cycling rate of thetool is selectively controlled. As soon as the cycling valve spool 110is shifted to its downward position, pressure will once again be appliedto the upper surface of the ring valve 40 in like manner as described inconnection with FIG. 10. Specifically the reservoir fluid from thetrigger port 162 will flow through passageway 198 and cyclingpassageways 122 and 48a, through passageway 48 to the upper surface ofthe ring member 40. At the same time the air pressure below the piston26, effective to return the drive piston 26 upwardly through a returnstroke, will be depleted by leakage through the bleed opening 71. Thepressure of the fluid in the closed upper end of the portion 108a of thecycling valve cylinder 108 will be bled off the atmosphere and thereturn bias pressure acting on the differential diameter portion of thecycling valve spool 110, applied through the trigger port 162,passageway 164, trigger ports 154 and 156, passageway 158, and safetyport 124, will be effective to more or shift the cycling valve spool 110back to its upper position, to the position illustrated in FIG. 9. Atthis point the cycling valve 82 is reset to exhaust the cylinder valveassembly and to repeat the cycling operation of the tool.

Although the present invention has been described by reference to only asingle embodiment, it will become apparent that numerous modificationsand embodiments may be devised by those skilled in the art, and it isintended by the appended claims to cover all modifications andembodiments which will fall within the true spirit and scope of thepresent invention.

What is claimed and desired to be secured by Letters Patent of TheUnited States is:

l. A pneumatically operated fastener driving tool including a housinghaving a cavity defining a fluid reservoir; a cylinder in said housing;a piston slideably mounted in the cylinder; main valve means controllingadmission of fluid to and the exhaustion of fluid from one end of thecylinder; pneumatic piston return means including a return air chamber,a cycling valve having a body defining a cycling valve cylinder of thedifferential type having a small and a large diameter portion and aspool valve element in said cylinder movable through a stroke from afirst to a second position, said spool valve ele# ment having large andsmall diameter portions slideable in the corresponding portions of thecycling valve cylinder and having a first sealing means on the largediameter portion of the spool valve element and a pair of spaced secondand third sealing means on the small diameter portion of the spool valveelement, said body having means defining a first port in the end of saidsmall diameter portion of the cycling valve cylinder. first passagewaymeans extending from said first port, a second port intermediate thestroke of the third sealing means, second passageway means connectingsaid second port to said main valve means, a third port opening betweenthe second and third sealing means, throughout their stroke, thirdpassageway means connecting said third port to said fluid reservoir, afourth port opening between the first sealing means and the secondsealing means throughout their travel, fourth passageway means extendingfrom said fourth port, a fifth port in the end of said large diameterportion of the cycling valve cylinder, fifth passageway means extendingfrom said fifth port to a source of signal fluid, and control means forselectively connecting said first and fourth passageways to saidreservoir and to exhaust.

2. A fastener driving tool as set forth in claim 1 wherein said controlmeans includes a trigger valve movable between a first positionexhausting said fourth port, a second position exhausting said firstport to provide single-fire operation of said tool, and a third positionconnecting said fourth port to the reservoir to provide multiple-fireoperation of said tool.

3. A fastener driving tool as set forth in claim 2 and including asafety valve in said first passageway movable between a safety positionconnecting said first port to said reservoir and a second positionconnecting said first port to said trigger valve for exhaust thereby.

4. A pneumatically operated fastener driving tool as set forth in claim1 and including metering means in said fifth passageway regulating therepetitive firing rate of said tool without affecting the single-firerate thereof.

5. A pneumatically operated fastener driving tool as set forth in claim1 wherein said fifth passageway opens into said return air chamber.

6. A pneumatically operated fastener driving tool including a pistonslideably mounted in a cylinder and movable through a driving and returnstroke, control means including manually operable means operable from anormal position to a first operated position for selectively operatingsaid tool through a single-fire operation, wherein said pistonautomatically moves through a single driving and return cycle while saidmanually operable means remains in said first operated position, saidmanually operable means being movable to a second operated position toeffect a multiple-fire operation wherein said piston automatically andcontinuously moves through repetitive cycles of driving and returnstrokes,,and means for adjustably regulating the repetitive cycling rateof said tool during said multiple-fire operation without altering thesingle firing cycling speed thereof.

7. A pneumatically operated fastener driving tool as set forth in claim6 wherein said tool includes a cycling valve movable between a normalposition controlling a power stroke and an actuated position providingthe return stroke, and means selectively providing for retention of saidcycling valve in said actuated position and for cycling said cyclingvalve in response to a cycling signal.

8. A pneumatically operated fastener driving tool comprising a drivingmember operable through cycles of power and return strokes, controlmeans selectively positionable to a first position to automaticallyoperate said driving member through a single cycle with the controlmeans held in the first position and to a second position toautomatically operate said driving member through repetitive cycles withthe control means held in the second position, and means for adjustablyregulating the repetitive cycling rate without altering the single cyclespeed thereof.

9. A fastener driving tool as set forth in claim 8 and including acycling valve controlling the movement of said driving 1 member throughits strokes, said cycling valve having a differential diameter portiondefining first and second surfaces of different area, first passagemeans connecting said first surface area to a source of signal fluid,and second passage means connecting said second surface area selectivelyto the atmosphere and to a source of pressurized fluid in response tothe selective setting of said control means to said first and secondpositions for single-cycle operation and multifire operation.

10. A fastener driving tool as set forth in claim 9 and includingadjustable means for throttling the fluid flow in said first passage.

11. A fluid-operated fastener driving tool comprising a driving memberoperable through a cycle of a power stroke and a return stroke, a mainvalve assembly operable to apply fluid to and to exhaust fluid from thedriving member to move the driving member through its power and returnstrokes, a cycling valve operable between spaced positions to controlthe operation of the main valve assembly, and manually operable controlmeans operable from a normal position to a single cycle position tocontrol the main valve and the cycling valve to effect a single cycle ofthe driving member while the manually operable control means remains insaid single cycle position, said manually operable control means beingoperable to a second position to control the main valve assembly and thecycling valve to automatically and continually move said driving memberthrough successive and repeated cycles so long as the manuallycontrolled means remains in said second position.

12. The tool set forth in claim 11 in which the manually operablecontrol means includes means operable in one of said first and secondpositions for applying a bias to the cycling valve and operable inthe-other of said first and second positions to prevent the applicationof a bias to the cycling valve.

13. A fluid-actuated fastener driving tool operable through a singlecycle of a power stroke and a return stroke or a number of cycles eachincluding a power stroke and a return stroke, said tool comprising acylinder, a piston slideable in the cylinder, fluid-actuated main valvemeans for alternately supplying fluid to and exhausting fluid from thecylinder to move the piston through the power stroke and a returnstroke, respectively, a cycling valve operable between two spacedpositions and coupled to the main valve means for selectivelycontrolling the connection of the main valve means to fluid and theatmosphere, said cycling valve being coupled to receive fluid admittedto the cylinder by the main valve means and operable to one of its twospaced positions thereby on each tool operation to institute the returnstroke of the piston, and manual control means operable from a normalposition to a first position to control the cycling valve to remain insaid one position until the manual control means is returned to itsnormal position so that the tool automatically operates through a singlecycle, said manual control means also being operable from a normalposition to a second position to control the cycling valve to move fromsaid one position to the other of its positions on each return stroke solong as the manual control means is held in its second position so thatthe tool automatically operates through a number of cycles.

14. The tool set forth in claim 13 in which the cycling valve includes adifferential piston operator and the manual control means includes avalve for selectively connecting the differential piston to theatmosphere and fluid.

15. A pneumatically operated fastener driving tool including a housing,a cylinder in said housing, a piston slidably mounted in said cylinderfor movement through power and return strokes, cylinder valve means forcontrolling the admission and exhaust of fluid from one end of saidcylinder to drive said piston through a power stroke and permit returnthereof, cushioning means positioned in the other end of said cylinderin the path of said piston to stop and cushion power strokes thereof ata normal piston stopping point, an air return chamber, first port meansadjacent the cushioning means for supplying air from the chamber beneaththe piston to move the piston through a return stroke, means forsupplying pressurized air to the chamber incident to each power stroke,and second port means spaced above the first port means and placing thechamber in communication with the cylinder, said second port means beingso spaced relative to the cushioning means that when the cushioningmeans deteriorates a given amount, the piston moves downwardly beyondthe normal piston stopping point and the second port means become openedto discharge pressurized air from the chamber into the cylinder abovethe piston, the second port means being of such size that the airdischarged renders the air in the chamber ineffective to move the pistonthrough a return stroke.

16. The fastener driving tool set forth in claim 15 in which the pistoncarries a sealing means disposed between said one end of the cylinderand the second port means when the piston is at its normal stoppingpoint and disposed between said first and second port means when thecushioning means deteriorates said given amount.

17. The fastener driving tool set forth in claim 16 in which the meansfor supplying pressurized air to the chamber includes a passage throughthe piston and opening into the cylinder between said sealing means andsaid other end of the cylinder.

18. A fluid-actuated fastener driving tool operable through a singlecycle of a power stroke and a return stroke or a number of cycles eachincluding a power stroke and a return stroke, said tool comprising acylinder, a piston slideable in the cylinder, fluid-actuated main valvemeans for alternately supplying fluid to and exhausting fluid from thecylinder to move the piston through the power stroke and the returnstroke, respectively, a cycling valve operable between two spacedpositions and coupled to the main valve means for selectivelycontrolling the connection of the main valve means to fluid and theatmosphere, said cycling valve being coupled to receive fluid admittedto the cylinder by the main valve means and operable to one of its twospaced positions thereby on each tool operation to institute the returnstroke of the piston, and manual means coupled to the cycling valve andthe main valve means for selectively controlling operation of the toolthrough a single cycle or a number of cycles, said control meansincluding first valve means operable between operated and releasedpositions for selectively supplying a connection to fluid and theatmosphere to operate the too], said manual control means also includinga second valve means, said second valve means being operable to a firstposition to control the cycling valve to remain in said one positionuntil the first valve means is returned to its released position so thatthe tool automatically operates through only a single cycle, said secondvalve means also being operable to a second position to control thecycling valve to move from said one position to the other of itspositions on each return stroke so long as the first valve means is inits operated position so that the tool operates through a number ofcycles.

19. The tool set forth in claim 18 in which the cycling valve includes adifferential piston operator with two fluid surfaces, one of saidsurfaces receiving fluid admitted to the cylinder by the main valvemeans, and in which the second valve means selectively connects theother of said surfaces to the atmosphere and fluid.

1. A pneumatically operated fastener driving tool including a housinghaving a cavity defining a fluid reservoir; a cylinder in said housing;a piston slideably mounted in the cylinder; main valve means controllingadmission of fluid to and the exhaustion of fluid from one end of thecylinder; pneumatic piston return means including a return air chamber,a cycling valve having a body defining a cycling valve cylinder of thedifferential type having a small and a large diameter portion and aspool valve element in said cylinder movable through a stroke from afirst to a second position, said spool valve element having large andsmall diameter portions slideable in the corresponding portions of thecycling valve cylinder and having a first sealing means on the largediameter portion of the spool valve element and a pair of spaced secondand third sealing means on the small diameter portion of the spool valveelement, said body having means defining a first port in the end of saidsmall diameter portion of the cycling valve cylinder, first passagewaymeans extending from said first port, a second port intermediate thestroke of the third sealing means, second passageway means connectingsaid second port to said main valve means, a third port opening betweenthe second and third sealing means, throughout their stroke, thirdpassageway means connecting said third port to said fluid reservoir, afourth port opening between the first sealing means and the secondsealing means throughout their travel, fourth passageway means extendingfrom said fourth port, a fifth port in the end of said large diameterportion of the cycling valve cylinder, fifth passageway means extendingfrom said fifth port to a source of signal fluid, and control means forselectIvely connecting said first and fourth passageways to saidreservoir and to exhaust.
 2. A fastener driving tool as set forth inclaim 1 wherein said control means includes a trigger valve movablebetween a first position exhausting said fourth port, a second positionexhausting said first port to provide single-fire operation of saidtool, and a third position connecting said fourth port to the reservoirto provide multiple-fire operation of said tool.
 3. A fastener drivingtool as set forth in claim 2 and including a safety valve in said firstpassageway movable between a safety position connecting said first portto said reservoir and a second position connecting said first port tosaid trigger valve for exhaust thereby.
 4. A pneumatically operatedfastener driving tool as set forth in claim 1 and including meteringmeans in said fifth passageway regulating the repetitive firing rate ofsaid tool without affecting the single-fire rate thereof.
 5. Apneumatically operated fastener driving tool as set forth in claim 1wherein said fifth passageway opens into said return air chamber.
 6. Apneumatically operated fastener driving tool including a pistonslideably mounted in a cylinder and movable through a driving and returnstroke, control means including manually operable means operable from anormal position to a first operated position for selectively operatingsaid tool through a single-fire operation, wherein said pistonautomatically moves through a single driving and return cycle while saidmanually operable means remains in said first operated position, saidmanually operable means being movable to a second operated position toeffect a multiple-fire operation wherein said piston automatically andcontinuously moves through repetitive cycles of driving and returnstrokes, and means for adjustably regulating the repetitive cycling rateof said tool during said multiple-fire operation without altering thesingle firing cycling speed thereof.
 7. A pneumatically operatedfastener driving tool as set forth in claim 6 wherein said tool includesa cycling valve movable between a normal position controlling a powerstroke and an actuated position providing the return stroke, and meansselectively providing for retention of said cycling valve in saidactuated position and for cycling said cycling valve in response to acycling signal.
 8. A pneumatically operated fastener driving toolcomprising a driving member operable through cycles of power and returnstrokes, control means selectively positionable to a first position toautomatically operate said driving member through a single cycle withthe control means held in the first position and to a second position toautomatically operate said driving member through repetitive cycles withthe control means held in the second position, and means for adjustablyregulating the repetitive cycling rate without altering the single cyclespeed thereof.
 9. A fastener driving tool as set forth in claim 8 andincluding a cycling valve controlling the movement of said drivingmember through its strokes, said cycling valve having a differentialdiameter portion defining first and second surfaces of different area,first passage means connecting said first surface area to a source ofsignal fluid, and second passage means connecting said second surfacearea selectively to the atmosphere and to a source of pressurized fluidin response to the selective setting of said control means to said firstand second positions for single-cycle operation and multifire operation.10. A fastener driving tool as set forth in claim 9 and includingadjustable means for throttling the fluid flow in said first passage.11. A fluid-operated fastener driving tool comprising a driving memberoperable through a cycle of a power stroke and a return stroke, a mainvalve assembly operable to apply fluid to and to exhaust fluid from thedriving member to move the driving member through its power and returnstrokes, a cycling valve opErable between spaced positions to controlthe operation of the main valve assembly, and manually operable controlmeans operable from a normal position to a single cycle position tocontrol the main valve and the cycling valve to effect a single cycle ofthe driving member while the manually operable control means remains insaid single cycle position, said manually operable control means beingoperable to a second position to control the main valve assembly and thecycling valve to automatically and continually move said driving memberthrough successive and repeated cycles so long as the manuallycontrolled means remains in said second position.
 12. The tool set forthin claim 11 in which the manually operable control means includes meansoperable in one of said first and second positions for applying a biasto the cycling valve and operable in the other of said first and secondpositions to prevent the application of a bias to the cycling valve. 13.A fluid-actuated fastener driving tool operable through a single cycleof a power stroke and a return stroke or a number of cycles eachincluding a power stroke and a return stroke, said tool comprising acylinder, a piston slideable in the cylinder, fluid-actuated main valvemeans for alternately supplying fluid to and exhausting fluid from thecylinder to move the piston through the power stroke and a returnstroke, respectively, a cycling valve operable between two spacedpositions and coupled to the main valve means for selectivelycontrolling the connection of the main valve means to fluid and theatmosphere, said cycling valve being coupled to receive fluid admittedto the cylinder by the main valve means and operable to one of its twospaced positions thereby on each tool operation to institute the returnstroke of the piston, and manual control means operable from a normalposition to a first position to control the cycling valve to remain insaid one position until the manual control means is returned to itsnormal position so that the tool automatically operates through a singlecycle, said manual control means also being operable from a normalposition to a second position to control the cycling valve to move fromsaid one position to the other of its positions on each return stroke solong as the manual control means is held in its second position so thatthe tool automatically operates through a number of cycles.
 14. The toolset forth in claim 13 in which the cycling valve includes a differentialpiston operator and the manual control means includes a valve forselectively connecting the differential piston to the atmosphere andfluid.
 15. A pneumatically operated fastener driving tool including ahousing, a cylinder in said housing, a piston slidably mounted in saidcylinder for movement through power and return strokes, cylinder valvemeans for controlling the admission and exhaust of fluid from one end ofsaid cylinder to drive said piston through a power stroke and permitreturn thereof, cushioning means positioned in the other end of saidcylinder in the path of said piston to stop and cushion power strokesthereof at a normal piston stopping point, an air return chamber, firstport means adjacent the cushioning means for supplying air from thechamber beneath the piston to move the piston through a return stroke,means for supplying pressurized air to the chamber incident to eachpower stroke, and second port means spaced above the first port meansand placing the chamber in communication with the cylinder, said secondport means being so spaced relative to the cushioning means that whenthe cushioning means deteriorates a given amount, the piston movesdownwardly beyond the normal piston stopping point and the second portmeans become opened to discharge pressurized air from the chamber intothe cylinder above the piston, the second port means being of such sizethat the air discharged renders the air in the chamber ineffective tomove the piston through a return stroke.
 16. THe fastener driving toolset forth in claim 15 in which the piston carries a sealing meansdisposed between said one end of the cylinder and the second port meanswhen the piston is at its normal stopping point and disposed betweensaid first and second port means when the cushioning means deterioratessaid given amount.
 17. The fastener driving tool set forth in claim 16in which the means for supplying pressurized air to the chamber includesa passage through the piston and opening into the cylinder between saidsealing means and said other end of the cylinder.
 18. A fluid-actuatedfastener driving tool operable through a single cycle of a power strokeand a return stroke or a number of cycles each including a power strokeand a return stroke, said tool comprising a cylinder, a piston slideablein the cylinder, fluid-actuated main valve means for alternatelysupplying fluid to and exhausting fluid from the cylinder to move thepiston through the power stroke and the return stroke, respectively, acycling valve operable between two spaced positions and coupled to themain valve means for selectively controlling the connection of the mainvalve means to fluid and the atmosphere, said cycling valve beingcoupled to receive fluid admitted to the cylinder by the main valvemeans and operable to one of its two spaced positions thereby on eachtool operation to institute the return stroke of the piston, and manualmeans coupled to the cycling valve and the main valve means forselectively controlling operation of the tool through a single cycle ora number of cycles, said control means including first valve meansoperable between operated and released positions for selectivelysupplying a connection to fluid and the atmosphere to operate the tool,said manual control means also including a second valve means, saidsecond valve means being operable to a first position to control thecycling valve to remain in said one position until the first valve meansis returned to its released position so that the tool automaticallyoperates through only a single cycle, said second valve means also beingoperable to a second position to control the cycling valve to move fromsaid one position to the other of its positions on each return stroke solong as the first valve means is in its operated position so that thetool operates through a number of cycles.
 19. The tool set forth inclaim 18 in which the cycling valve includes a differential pistonoperator with two fluid surfaces, one of said surfaces receiving fluidadmitted to the cylinder by the main valve means, and in which thesecond valve means selectively connects the other of said surfaces tothe atmosphere and fluid.